A synthetic approach to cytochalasin D and analogs is the principal goal of this project. A major subgoal is to develop new methods for synthesis of large ring heterocycles and carbocycles. A technique for 3-carbon ring expansion by 2,3-sigmatropic shift of alpha-vinyl heterocycles via the derived ammonium or sulfonium ylids has been developed. Variations of this approach are to be used for synthesis of the 11-membered ring of cytochalasin D. The AB ring system will be assembled by a Diels-Alder route. Suitable dienophiles consisting of an alpha, beta-saturated butyrolactam subunit will be condensed with dienes to prepare the AB rings. BIBLIOGRAPHIC REFERENCES: "Fragmentation of Ester-stabilized Ammonium Ylids to Alkenes", E. Vedejs and D.A. Engler, Tetrahedron Let., (1977), in press. "Reactive Triflate Alkylating Agents", E. Vedejs, D.A. Engler, and M. Mullins, J. Org. Chem. 42, (1977), in press.